The billionaire businessman turned president had promised to forgo his presidential salary. By law he must be paid, so he is donating the money.

Zinke says he's "thrilled" at the president's decision to give money to an Interior agency, something he says Trump informed him about Sunday night. He says he will use the money to help on long-deferred maintenance projects on the nation's 25 battlefields.

Trump's has proposed cutting $120 million - or 12 percent - from the Interior Department's budget.